diff --git a/sql/catalyst/src/main/java/org/apache/spark/sql/catalyst/expressions/UnsafeRow.java b/sql/catalyst/src/main/java/org/apache/spark/sql/catalyst/expressions/UnsafeRow.java
index af687eaeb8ab4..5555b54684af1 100644
--- a/sql/catalyst/src/main/java/org/apache/spark/sql/catalyst/expressions/UnsafeRow.java
+++ b/sql/catalyst/src/main/java/org/apache/spark/sql/catalyst/expressions/UnsafeRow.java
@@ -30,6 +30,7 @@
 import java.util.HashSet;
 import java.util.Set;
 
+import org.apache.spark.sql.catalyst.InternalRow;
 import org.apache.spark.sql.types.ArrayType;
 import org.apache.spark.sql.types.BinaryType;
 import org.apache.spark.sql.types.BooleanType;
@@ -610,8 +611,12 @@ public boolean equals(Object other) {
       return (sizeInBytes == o.sizeInBytes) &&
         ByteArrayMethods.arrayEquals(baseObject, baseOffset, o.baseObject, o.baseOffset,
           sizeInBytes);
+    } else if (other == null || !(other instanceof InternalRow)) {
+      return false;
+    } else {
+      throw new IllegalArgumentException(
+        "Cannot compare UnsafeRow to " + other.getClass().getName());
     }
-    return false;
   }
 
   /**
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/execution/Window.scala b/sql/core/src/main/scala/org/apache/spark/sql/execution/Window.scala
index b1280c32a6a43..b3f1580c2784a 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/execution/Window.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/execution/Window.scala
@@ -96,6 +96,7 @@ case class Window(
   override def outputOrdering: Seq[SortOrder] = child.outputOrdering
 
   override def canProcessUnsafeRows: Boolean = true
+  override def outputsUnsafeRows: Boolean = false
 
   /**
    * Create a bound ordering object for a given frame type and offset. A bound ordering object is
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/execution/basicOperators.scala b/sql/core/src/main/scala/org/apache/spark/sql/execution/basicOperators.scala
index a42aea0b96d43..58d5669c9c19d 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/execution/basicOperators.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/execution/basicOperators.scala
@@ -251,6 +251,7 @@ case class Coalesce(numPartitions: Int, child: SparkPlan) extends UnaryNode {
   }
 
   override def canProcessUnsafeRows: Boolean = true
+  override def outputsUnsafeRows: Boolean = child.outputsUnsafeRows
 }
 
 /**
@@ -319,6 +320,7 @@ case class AppendColumns[T, U](
   // We are using an unsafe combiner.
   override def canProcessSafeRows: Boolean = false
   override def canProcessUnsafeRows: Boolean = true
+  override def outputsUnsafeRows: Boolean = true
 
   override def output: Seq[Attribute] = child.output ++ newColumns
 
@@ -326,10 +328,11 @@ case class AppendColumns[T, U](
     child.execute().mapPartitionsInternal { iter =>
       val tBoundEncoder = tEncoder.bind(child.output)
       val combiner = GenerateUnsafeRowJoiner.create(tEncoder.schema, uEncoder.schema)
-      iter.map { row =>
+      val unsafeRows: Iterator[UnsafeRow] = iter.map { row =>
         val newColumns = uEncoder.toRow(func(tBoundEncoder.fromRow(row)))
-        combiner.join(row.asInstanceOf[UnsafeRow], newColumns.asInstanceOf[UnsafeRow]): InternalRow
+        combiner.join(row.asInstanceOf[UnsafeRow], newColumns.asInstanceOf[UnsafeRow])
       }
+      unsafeRows
     }
   }
 }